In disc brake systems, it is common to employ return springs that return the disc brake pads to a rest position after braking. These springs come in a variety of shapes, including v-shapes. Typically, the ends of the springs engage the upper parts of the backing plates that support the brake, or friction pads. FIG. 1 is a partial top view 10 of a typical disc brake assembly wherein a v-shaped spring 1 is positioned between backing plates 3 that support friction pads 5. The v-shaped spring 1 exerts an outward force “F” on the pads 5 to urge each pad 5 away from respective outer surfaces 8 of the rotor 7, thus preventing drag, excessive pad wear, and excessive rotor wear during the non-braking condition.
FIG. 2 illustrates the spring 1 in a typical installation and shows one of two opposed ears 9 that are commonly used to carry the backing plate. The ears 9 ride in a recess 12 in the mounting member 14. Engagement legs 11 at the end of each spring member 13 engage openings 15 in the backing plates 3. As shown in FIG. 4, the engagement legs 11 are perpendicular to the spring member 13. When positioned in the opening 15 in the backing plate 3 (see FIG. 3) the engagement leg 11 is generally parallel to the opposing sides of the opening 15.
FIG. 5 illustrates a problem created by the return spring shown in FIGS. 1-4. The forces applied by the spring 13 to the upper parts of the backing plates 3 create a torque that rotates the pads about the ears 9 when the system is in a non-braking state. Thus, the plates 3 rotate about a longitudinal axis “M” of the plate (see FIG. 2) that extends in a tangential direction (with respect to the brake rotor) between the ears 9, which causes the pads 5 to assume a non-parallel configuration with respect to the rotor 7, whereby the bottoms of the pads often contact the rotor 7 in the areas 16 resulting in uneven pad wear and excessive drag.
Accordingly, a need exists to reduce or eliminate the uneven wear and drag that result from the configuration shown in FIG. 5 to increase friction pad and rotor life. The invention responds to this need by providing a uniquely configured disc brake pad return spring that applies a force urging the pads away from the rotor and also applies a twisting force that prevents the rotation about the backing plate ears normally caused by the return spring force.